According to TMZ, Ross, 34, has hired celebrity lawyer Laura Wasser, who has also handled cases for Kim Kardashian, Britney Spears, and Heidi Klum, and is asking for joint custody of their children — seven-year-old Skyla and five-year-old Tennyson — as well as spousal support.

Sanders, 41, who is represented by attorney Lance Spiegel, has reportedly filed a response to the petition and is also asking for joint custody. While Sanders is not seeking spousal support, he has requested that the cost of the proceedings are split with Ross.

Ross and Sander’s nine-year-marriage was subjected to worldwide scrutiny after explosive pictures of Sanders and actress Kristen Stewart were published last July by Us Weekly magazine.

During the resulting furor, both Ross and Sanders’ relationship and Stewart and Robert Pattinson’s came under intense speculation during promotion for both TheTwilight Saga: Breaking Dawn – Part 2, and Pattinson’s Cosmopolis.

At the time, Stewart released a public apology in People.com. Sanders released a similar statement, saying:

“I am utterly distraught about the pain I have caused my family. My beautiful wife and heavenly children are all I have in this world. I love them with all my heart. I am praying that we can get through this together.”

Since then, Stewart, 22, has rekindled her relationship with Pattinson, while Ross — who played Stewart’s mother in the first film — reportedly insisted that Sanders step away from the Snow White and The Huntsman sequel, the Los Angeles Times reports.

Despite reports last year that Ross and Sanders were attempting to salvage their relationship and attending therapy sessions, the estranged couple have not been seen publicly together for some months.

“I believe we’re all on journeys and we are all given lessons at certain times in our life, and sometimes when things seem really bad you have to be able to see the good and learn from it. And just move forward as graciously as possible.”